BACKGROUND: Understanding antibody responses to SARS-CoV-2 vaccination is crucial for refining COVID-19 immunization strategies. Generation of mucosal immune responses, including mucosal IgA, could be of potential benefit to vaccine efficacy, yet limited evidence exists regarding the production of mucosal antibodies following the administration of current mRNA vaccines to young children.
METHODS: We measured the levels of antibodies against SARS-CoV-2 from a cohort of children under 5 years of age (N=24) undergoing SARS-CoV-2 mRNA vaccination (serially collected, matched serum and saliva samples) or in a convenience sample of children under 5 years of age presenting to pediatric emergency department (nasal swabs, N=103). Further, we assessed salivary and nasal samples for the ability to induce SARS-CoV-2 spike-mediated neutrophil extracellular traps (NET) formation.
RESULTS: Longitudinal analysis of post-vaccine responses in saliva revealed the induction of SARS-CoV-2 specific IgG but not IgA. Similarly, SARS-CoV-2 specific IgA was only observed in nasal samples obtained from previously infected children with or without vaccination, but not in vaccinated children without a history of infection. In addition, oronasopharyngeal samples obtained from children with prior infection were able to trigger enhanced spike-mediated NET formation, and IgA played a key role in driving this process.
CONCLUSIONS: Despite the induction of specific IgG in the oronasal mucosa, current intramuscular vaccines have limited ability to generate mucosal IgA in young children. These results confirm the independence of mucosal IgA responses from systemic humoral responses following mRNA vaccination and suggest potential future vaccination strategies for enhancing mucosal protection in this young age group.

The inducers of neutrophil extracellular trap (NET) formation are heterogeneous and consequently, there is no specific pathway or signature molecule indispensable for NET formation. But certain events such as histone modification, chromatin decondensation, nuclear envelope breakdown, and NET release are ubiquitous. During NET formation, neutrophils drastically rearrange their cytoplasmic, granular and nuclear content. Yet, the exact mechanism for decoding each step during NET formation still remains elusive. Here, we investigated the mechanism of nuclear envelope breakdown during NET formation. Immunofluorescence microscopic evaluation revealed a gradual disintegration of outer nuclear membrane protein nesprin-1 and alterations in nuclear morphology during NET formation. MALDI-TOF analysis of NETs that had been generated by various inducers detected the accumulation of nesprin-1 fragments. This suggests that nesprin-1 degradation occurs before NET release. In the presence of a calpain-1, inhibitor nesprin-1 degradation was decreased in calcium driven NET formation. Microscopic evaluation confirmed that the disintegration of the lamin B receptor (LBR) and the collapse of the actin cytoskeleton occurs in early and later phases of NET release, respectively. We conclude that the calpain-1 degrades nesprin-1, orchestrates the weakening of the nuclear membrane, contributes to LBR disintegration, and promoting DNA release and finally, NETs formation.

Postoperative breast cancer recurrence is tricky due to the limited therapeutic options. Transforming growth factors-β (TGF-β) is vital in promoting postoperative tumor recurrence. However, conventional blocking strategies fail to satisfy both bio-safety and sufficient relapse correction. Neutrophil extracellular traps (NETs) are essential for the spatiotemporal dynamics of TGF-β at tumor-resection sites, whose unique mechanism for local TGF-β amplification could remarkably increase the risk of relapse after surgery. Herein, the principle of NETs formation is ingeniously utilized to construct a surgical residual cavity hydrogel that mimics NETs formation. The hydrogel is prepared based on the electrostatic interaction between histidine (His) and sodium alginate (Alg). Then, arginine deiminase 4 (PAD4) protein is released during NETs formation. Simultaneously, the electrical property of His in hydrogel changes automatically, which further lead to promising localized release of anti-TGF-β. The hydrogel system can realize specific and selective drug release at targeted NETs site over a prolonged period while exhibiting excellent biocompatibility. Superior breast cancer recurrence inhibition is achieved by suppressing TGF-β and related indicators, impeding epithelial-mesenchymal transition (EMT) progression, and rectifying the locally exacerbated immunosuppressive environment within NETs. The novel NETs local microenvironment drug release functional hydrogel will provide inspiration for postoperative recurrence correction strategies.

BACKGROUND: Hyperlipidemia is one of the main causes of aggravated hepatic ischemia-reperfusion injury (IRI). Simvastatin (SIM), a lipid-lowering drug, has been shown to effectively alleviate IRI caused by hyperlipidemia. However, the regulatory mechanism by which SIM alleviates hyperlipidemia-induced hepatic IRI is still not clear. This study aims to explore the potential mechanisms of SIM in inhibiting hyperlipidemia-induced hepatic IRI, providing new therapeutic strategies for the alleviation of hepatic IRI.
METHODS: An animal model of hyperlipidemia was induced by feeding mice a high-fat diet for 8 weeks. Subsequently, a hepatic IRI animal model of hyperlipidemia was established by occluding the hepatic artery and portal vein for one hour, followed by reperfusion for 6 or 12 h. Enzyme linked immunosorbent assay, Western blotting, hematoxylin-eosin (H&E) staining, immunohistochemistry, immunofluorescence, and Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling assay, were used to evaluate liver injury, neutrophil extracellular traps (NETs) formation, and related molecular mechanisms.
RESULTS: Hepatic IRI was accelerated by hyperlipidemia, which enhanced the expression of oxidized low-density lipoprotein (oxLDL) and Macrophage-1antigen (Mac-1), leading to the promotion of NETs formation and apoptosis of liver cells. The administration of simvastatin reduced the levels of oxLDL and Mac-1, decreased the formation of NETs, and alleviated hepatic IRI induced by hyperlipidemia.
CONCLUSIONS: Simvastatin reduced hyperlipidemia-induced hepatic IRI by inhibiting the formation of NETs through the regulation of the oxLDL/Mac-1 pathway.

Neutrophil extracellular traps (NETs), extrusions of intracellular DNA with attached granular material that exert an antibacterial effect through entangling, isolating, and immobilizing microorganisms, have been extensively studied in recent decades. The primary role of NETs is to entrap and facilitate the killing of bacteria, fungi, viruses, and parasites, preventing bacterial and fungal dissemination. NET formation has been described in many pulmonary diseases, including both infectious and non-infectious. NETs are considered a double-edged sword. As innate immune cells, neutrophils release NETs to kill pathogens and remove cellular debris. However, the deleterious effects of excessive NET release in lung disease are particularly important because NETs and by-products of NETosis can directly induce epithelial and endothelial cell death while simultaneously inducing inflammatory cytokine secretion and immune-mediated thrombosis. Thus, NET formation must be tightly regulated to preserve the anti-microbial capability of NETs while minimizing damage to the host. In this review, we summarized the recent updates on the mechanism of NETs formation and pathophysiology associated with excessive NETs, aiming to provide insights for research and treatment of pulmonary infectious diseases.

Resident physicians on long-term night shifts often face sleep deprivation, affecting the immune response, notably neutrophils, vital to innate defense mechanisms. Sleep-deprived residents exhibit altered neutrophil counts and reduced phagocytosis and NADPH oxidase activity, critical to combating infections. Our study focused on neutrophil extracellular traps (NETs), a defense process against pathogens not previously linked to sleep loss. Results revealed that sleep-deprived residents exhibited a 19.8 % reduction in NET formation compared to hospital workers with regular sleep patterns (P < 0.01). Additionally, key NETs proteins, Neutrophil Elastase and Myeloperoxidase, were less active in sleep-deprived individuals (1.53mU; P < 0.01 and 0.95U; P < 0.001 decrease, accordingly). Interestingly, the ability to form NETs resumed to normal levels three months post-residency among pediatric residents. The causal relationship between reduced NETs due to sleep deprivation and the increased susceptibility to infections, as well as its implications for infection severity, is a critical area for further investigation.

BACKGROUND: Doxorubicin and cisplatin are both first-line chemotherapeutics for osteosarcoma (OS) treatment. However, the efficacy of doxorubicin/cisplatin chemotherapy varies considerably. Thus, identifying an efficient diagnostic biomarker to distinguish patients with good and poor responses to doxorubicin/cisplatin chemotherapy is of paramount importance.
METHODS: To predict the efficacy of doxorubicin/cisplatin chemotherapy, we analyzed the differentially expressed proteins in 37 resected OS samples, which were categorized into the primary group (PG), the recurrent group (RG) and the metastatic group (MG). The characteristics of the enriched differentially expressed proteins were assessed via GO and KEGG analyses. Protein‒protein interactions were identified to determine the relationships among the differentially expressed proteins. Receiver operating characteristic (ROC) curve analyses were performed to explore the clinical significance of the differentially expressed proteins. Parallel reaction monitoring (PRM) was used to validate the candidate proteins. Immunohistochemical (IHC) staining was performed to confirm the expression of cathepsin (CTSG) in patients with good and poor response to doxorubicin/cisplatin.
RESULTS: A total of 9458 proteins were identified and quantified, among which 143 and 208 exhibited significant changes (|log2FC|>1, p < 0.05) in the RG and MG compared with the PG, respectively. GO and KEGG enrichment led to the identification of neutrophil extracellular traps (NETs). ROC curve analyses revealed 74 and 86 proteins with areas under the curve greater than 0.7 in the RG and MG, respectively. PRM validation revealed the statistical significance of CTSG, which is involved in NET formation, at the protein level in both the RG and MG. IHC staining of another cohort revealed that CTSG was prominently upregulated in the poor response group after treatment with doxorubicin/cisplatin.
CONCLUSIONS: CTSG and its associated NETs are potential biomarkers with which the efficacy of doxorubicin/cisplatin chemotherapy could be predicted in OS patients.

UNASSIGNED: Cardiopulmonary bypass (CPB) can trigger a systemic inflammatory response during the perioperative period, which may lead to the consumption of the contact system and the production of neutrophil extracellular traps (NETs). This study attempted to determine whether the formation of NETs and contact activation are a vivid occurrence during CPB and whether they are related to post-operative atrial fibrillation (AF) and survival.
UNASSIGNED: A prospective observational study was conducted in 97 patients who underwent aortic valve and/or aorta replacement surgery with CPB. Circulating markers of NETs [histone-DNA complex, cell-free double stranded DNA (dsDNA), neutrophil elastase] and the contact system [prekallikrein, high molecular weight kininogen (HMWK), activated factor XII (FXIIa)] were measured at four-time points: before surgery (T0), immediately after surgery (T1), 1 day after surgery (T2), and 3 days after surgery (T3).
UNASSIGNED: Elevated levels of circulating NETs markers were observed across post-CPB time. Significantly elevated levels of histone-DNA complex and cell-free dsDNA measured T3 were detected in patients with post-operative AF compared to those without. In logistic regression analysis, levels of histone-DNA complex and cell-free dsDNA measured at T3 were significant markers of risk for occurrence of AF. The levels of cell-free dsDNA measured T2 were significantly higher in non-survivors than in survivors. The level of cell-free dsDNA showed significant prognostic value.
UNASSIGNED: NETs markers may be useful for the assessment of risk for post-operative AF and mortality. Conduct of additional research regarding the role of NETs as clinical markers and as a therapeutic target in CPB is anticipated.

OBJECTIVE: Neutrophils and neutrophil extracellular traps (NETs) contribute to the vascular complications of multiple diseases, but their role in systemic sclerosis (SSc) is understudied. We sought to test the hypothesis that NETs are implicated in SSc vasculopathy and that treatment with prostacyclin analogs may ameliorate SSc vasculopathy not only through vasodilation but also by inhibiting NET release.
METHODS: Blood from 125 patients with SSc (87 diffuse cutaneous SSc and 38 limited cutaneous SSc) was collected at a single academic medical center. Vascular complications such as digital ulcers, pulmonary artery hypertension, and scleroderma renal crisis were recorded. The association between circulating NETs and vascular complications was determined using in vitro and ex vivo assays. The impact of the synthetic prostacyclin analog epoprostenol on NET release was determined.
RESULTS: Neutrophil activation and NET release were elevated in patients with SSc-associated vascular complications compared to matched patients without vascular complications. Neutrophil activation and NETs positively correlated with soluble E-selectin and VCAM-1, circulating markers of vascular injury. Treatment of patients with digital ischemia with a synthetic prostacyclin analog boosted neutrophil cyclic AMP, which was associated with the blunting of NET release and reduced NETs in circulation.
CONCLUSIONS: Our study demonstrates an association between NETs and vascular complications in SSc. We also identified the potential for an additional therapeutic benefit of synthetic prostacyclin analogs, namely to reduce neutrophil hyperactivity and NET release in SSc patients.

UNASSIGNED: NETs, a unique neutrophil immune mechanism, are vital in defending against microbial invasions. Understanding the mechanisms of co-infection by Candida albicans and Staphylococcus aureus, which often leads to higher mortality and poorer prognosis, is crucial for studying infection progression.
UNASSIGNED: In our study, we established a mouse model of subcutaneous infection to characterize the inflammation induced by co-infection. By purifying and extracting NETs to interact with microorganisms, we delve into the differences in their interactions with various microbial species. Additionally, we investigated the differences in NETs production by neutrophils in response to single or mixed microorganisms through the interaction between neutrophils and these microorganisms. Furthermore, we analyzed the gene expression differences during co-infection using transcriptomics.
UNASSIGNED: In vivo, C. albicans infections tend to aggregate, while S. aureus infections are more diffuse. In cases of co-infection, S. aureus adheres to and wraps C. albicans. NETs exhibit strong killing capability against C. albicans but weaker efficacy against S. aureus. When NETs interact with mixed microorganisms, they preferentially target and kill the outer layer of S. aureus. In the early stages, neutrophils primarily rely on phagocytosis to kill S. aureus, but as the bacteria accumulate, they stimulate neutrophils to produce NETs. Interestingly, in the presence of neutrophils, S. aureus promotes the proliferation and hyphal growth of C. albicans.
UNASSIGNED: Our research has showed substantial differences in the progression of co-infections compared to single-microbial infections, thereby providing scientific evidence for NETs as potential therapeutic targets in the treatment of co-infections.